Home Hot Wash THMG182 – Hot Wash: Nitric Acid & Acetone

THMG182 – Hot Wash: Nitric Acid & Acetone


In this hot wash episode, Bob and Mike explore a listener-submitted incident involving a nitric acid and acetone explosion.

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Complete Show Notes

3:35 The Situation

  • On 2/12/19, a local 911 received a report of a chemical explosion at a lab in an R&D division of a company
  • Caller indicated there were no injuries
  • Dispatch indicated that the two chemicals involved were nitric acid and acetone
  • First due engine immediately requested the listener’s primary hazmat company, which subsequently made the immediate response for the secondary team
  • Total response included two engine companies, one battalion chief, one safety officer, the division chief, Hazmat 1 (captain, engineer, two firefighters), and Hazmat 2 (captain and two firefighters)
  • Total of six hazmat technicians on scene

4:45 Analysis from Bob & Mike

  • Bob would urge operations-level responders to start by immediately referencing the Emergency Response Guidebook (ERG)
  • Interview people on-scene and try to get the name of the chemical(s)
  • Medically evaluate and decon anybody who’s been hurt
  • Don’t touch anything (if you can help it) – if you do, do an emergency decon on yourself

7:25 Arriving On Scene

  • First arriving engine company assumed command and began a size-up of the building and situation
  • Representatives from the company indicated that a mixture of nitric acid and acetone had inadvertently been created and placed in the corner of a lab
  • Employee noticed evidence of an exothermic reaction (bubbling heat) and looked for a secure disposal area, but the lab didn’t have one
  • Initial incident commander procured MSDS sheets for both chemicals and had company personnel sketch a map of the incident area

8:20 Analysis from Bob & Mike

  • Both Bob and Mike have no problem with how operations-level personnel have handled things to this point
  • Having personnel sketch a map was a great idea since you need to know points of entry and egress

9:00 Info on the Lab

  • Approximately 1,000-1,200 square feet – one wall lined with cubicles and a large work area with all of the normal materials for a chemical research lab (except a safe place to discard potentially hazardous waste)
  • Container was a four-gallon carboy (typically glass) that had been placed on a rolling cart in the far corner of the lab area
  • There was a cubicle partition on one side of the cart and exterior walls on two sides
  • Team had access to the lab via the main entrance to the building with a long walk through hallways that led to the incident area

9:45 Analysis from Bob & Mike

  • This is a typical lab – isn’t anything special or out of the ordinary
  • A lot of positive and negative energy can form inside carboys, which makes them an explosion risk
  • Nitric acid is a corrosive, so your pH is going to move left and right
  • Acetone is flammable, which means your LEL is going to go up and down
  • In general, we want our meters to help us determine the hot zone

15:55 Determining the Hot Zone

  • Area of the lab that had controlled access through two doors was designated to be the hot zone
  • Corner of the lab that was directly involved in the explosion was visible through one door down a short hallway
  • Second door was used for hazmat team entry because it was a short hallway with a left turn to enter the lab and another left to get to the corner where the explosion occurred
  • Longer entry also allowed hazmat techs to use the emergency decon shower in the main hallway before going through decon outside the facility

16:40 Analysis from Bob & Mike

  • Remember that almost all facilities that have chemicals are going to have decon showers somewhere
  • These areas can also be used as technical decon areas – makes your cleanup easier and more efficient in the long run
  • It’s common for us to overlook things in our scene size-up – this is something we can all work on improving

19:45 Making Entry

  • Hazmat captains assumed roles of operations and hazmat safety and elected to use Level B suits for entry
  • Initial entry team consisted of two personnel with acid absorbent pads, Dräger tubes for nitric acid and acetone, pH paper, and a 5-gas meter set up for O2, CO, LEL, VOC, and H2S (standard 5-gas)
  • Goal for the two man team entering through the main hallway was to assess the situation for the presence and/or concentration of vapors, the amount of area involved, initial pH reading of the wet spill area, and, if possible, to stop any remaining reactions from taking place

20:45 Analysis from Bob & Mike

  • Again, Bob and Mike feel all of these actions are sound – can’t think of a single thing they’d do differently (wow!)
  • Might not necessarily use Dräger tubes, but have absolutely no problem with somebody else bringing them in

22:55 Role of Entry Team 1

  • Carboy had exploded and sprayed the area from floor to ceiling with the nitric acid/acetone mixture
  • Mixture was fluid, but some drying was taking place in the nearest cubicle and on vertical surfaces where the concentration of the liquid was minimal
  • Initial pH readings confirmed the presence of a strong acid
  • Air monitoring indicated a very slight VOC reading and 1 ppm reading of nitric acid
  • Entry Team 1 covered the spill area on the floor with absorbent pads and applied a thin layer of neutralization powder that was provided by the facility – always a good idea to use supplies facility has because they might have more expertise on specific chemicals than you do
  • Team then exited the lab through the main hallway and used the emergency shower in the hallway for a quick decon before exiting the building for simple water decon performed by an engine company staffed with hazmat operations-level firefighters

30:35 Role of Entry Team 2

  • Made entry in Level B suits to prevent contamination of turnout gear
  • Monitored conditions after initial mitigation measures
  • Applied more neutralizing agent to areas not previously treated and tested the material’s resulting pH
  • Once the material was brought back to a neutral state, Entry Team 2 exited the facility following the same decon procedure and path as Entry Team 1
  • Entry Team 1 made one additional sweep of the lab for air monitoring before the outside contractor began cleanup of the affected area

32:40 Analysis from Bob & Mike

  • Bob and Mike like the idea of using the showers in the hallway for quick decon
  • On the other hand, Bob isn’t sure this would work, and it’s different from what he’d do
  • Mike points out that you could mesh the two together – rinse/scrub/rinse in technical decon, check, and then send them on their way
  • Bob and Mike are totally cool with letting a contractor come in and do their job

33:20 Incident Takeaways from Listener

  • Learned there’s a generational gap between leadership and down-range techs
  • At the beginning of the run, it was a sealed scene with a strong acid – by the end, it was a strong base in different areas
  • They’d like to see more on-site incident to return the substance to neutral, rather than throwing around neutralizing agents
  • Didn’t feel team was prepared to address the scene as needed – feels more training is required for both hazmat teams and engine companies so they can better work together
  • Also need to train on neutralization before attempting to do it in the field
  • Issues aren’t unfixable, but will take time and effort to rectify
  • Built confidence in their ability to go downrange in an adverse environment to complete their assigned task

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